Editing Lady Windermere's Fan (section)

===Act IV===
The next day, Lady Windermere is lying on the couch of the morning room anxious about whether to tell her husband what actually happened, or whether Mrs Erlynne will have already betrayed her secret. Her husband enters. He is sympathetic towards her and suggests that as the London [[Season (society)|season]] is almost over that they head to their country estate to forget the recent incident. Lady Windermere apologises for her previous suspicion of her husband and behaviour at the party, and Lord Windermere makes clear his new contempt for Mrs Erlynne—warning his wife to stay away from her.

Mrs Erlynne's arrival is announced along with the return of the fan, and despite her husband's protestations, Lady Windermere insists on seeing her. Mrs Erlynne enters and states that she shall be going abroad, but asks that Lady Windermere give her a photograph of herself and her son.

Whilst Lady Windermere leaves the room to find one, the story is revealed: Mrs Erlynne left her husband for a lover shortly after Lady Windermere's birth. When her new lover abandoned her, Mrs Erlynne was left alone and in disrepute. More recently, using the assumed name of Mrs Erlynne, she has begun blackmailing Lord Windermere to regain her lifestyle and status, by threatening to reveal her true identity as Lady Windermere's shameful mother—not dead, as Lady Windermere believes. Her son-in-law, Lord Windermere laments not having told his wife the whole story at once and resolves to tell her the truth now. Mrs Erlynne forbids him to do so, threatening to spread shame far and wide if he does.

Lady Windermere returns with the photograph which she presents to Mrs Erlynne, and requests that Lord Windermere check for the return of Mrs Erlynne's coach. Now that they are alone, and being owed a favour, Mrs Erlynne demands that Lady Windermere not reveal the truth about the events of the previous night to Lord Windermere, and Lady Windermere promises to keep the secret.

After Lord Windermere's return, Lord Augustus enters. He is shocked to see Mrs Erlynne after the events of the night before, but she requests his company as she heads to her carriage, and he soon returns to the Windermeres with news that she has satisfactorily explained the events of the evening, and that they are to marry and live out of England.

{{Blockquote|Lady Windermere, taking her husband's hand, to Lord Augustus: "Ah, you're marrying a very good woman!"}}

Their marriage is restored, but both Lord and Lady Windermere keep their secrets.